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August 3rd, 2011, 11:23 PM  #1 
Senior Member Joined: Dec 2010 Posts: 233 Thanks: 0  Probability
1.Given that P(B)=1/2,P(B l A)=3/7, P(B l A' ) =2/3 Find P(A ? B) ,P( A U B ),P( A l B ) 2.If P( A l B )=3/10,P( B' l A ) =2/3,A and B are independent,find P(B),P(A U B),P(A' l B ). Please help me to solve the question step by step.I need help. 
August 4th, 2011, 03:22 AM  #2  
Member Joined: Aug 2011 From: Nouakchott, Mauritania Posts: 85 Thanks: 14 Math Focus: Algebra, Cryptography  Re: Probability Quote:
We know that P(A'=P(B  A)P(A)+P(BA'(1P(A))" /> So }{P(B  A)P(B  A'}=\frac{1/22/3}{3/72/3}=7/10" /> then also and finally What do you think ?  
August 4th, 2011, 09:34 PM  #3 
Senior Member Joined: Dec 2010 Posts: 233 Thanks: 0  Re: Probability
I still don understand about the part how do you come out the equation p(B)=P(B l A)P(A) + P(B l A' )P(A') and one part state that P(A ? B)=P(A)P(BlA) ,i don understand why.i need explanation. 
August 5th, 2011, 05:35 AM  #4  
Math Team Joined: Dec 2006 From: Lexington, MA Posts: 3,267 Thanks: 408  Re: Probability Hello, hoyy1kolko! Quote: [color=beige]. . [/color] Quote: [color=beige]. . [/color] [color=beige]. . [/color] [color=beige]. . [/color] [color=beige]. . [/color] Quote:
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August 6th, 2011, 05:09 AM  #5 
Senior Member Joined: Dec 2010 Posts: 233 Thanks: 0  Re: Probability
Thank for the excellent explanation.I get it now!! i still need some help. Two transistors are chosen at random from a batch of transistor containing ninety good and ten defective ones. a)If at least one out of the two transistors chosen is defective,find the probability that both transistors are defective. This are the part that i can't solve in this question.I need help.and explanation. 

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